The present invention relates to loudspeaker apparatus. More particularly, it relates to a loudspeaker apparatus of the kind having a speaker enclosure in which propagation out of the enclosure of the forwardly travelling sound energy of the loudspeaker is directly from the front of the loudspeaker, while propagation out of the enclosure of the backwardly travelling sound energy of the loudspeaker is by way of acoustic coupling means from the back of the loudspeaker.
Heretofore, the backwardly travelling sound energy of a loudspeaker has been propagated out of an enclosure from the back of the loudspeaker by acoustically coupling such sound energy to a passive radiator mounted on an exterior wall of the enclosure or to a port provided through an exterior wall of the enclosure. In either case, the known arrangements have not optimally used the acoustic space in the enclosure while providing a minimum amount of standing-wave motion and have not optimally controlled the direction of acoustic energy travel while preventing establishment of internal or structural resonances. Such known arrangements have moreover been deficient in providing a compression capability for producing an acoustic restoring force to dampen mechanical overshooting of a loudspeaker at low frequencies and extending low frequency response, as well as in minimizing harmonic distortion at fundamental frequencies.